emi gaskets

EMI Gaskets try to achieve two things:

  1. They try to shield electronics from EMI/RFI waves that are inherent in our daily lives now, OR conduct electricity in a certain direction to avoid electrostatic discharge to the wrong places. Sometimes they do both.
  2. They serve as environmental seals/gaskets. Each EMI Shielding product varies in how well, and what it seals against. For example, most EMI gaskets are made of silicone, thus being good at sealing in high temperature environments. As another example, fluorosilicone is used in fuel laden applications. 

One thing most EMI/RFI shielding products are not good at, is avoiding extrusion under pressure. In fact, I view most EMI/RFI shielding products are fairly weak, and wouldn’t recommend a compression value of more than 25% on any flat gasket- and there should be compression stops. I’ve seen way too many EMI/RFI shielding products extrude under improper pressure, or compression. With that said, I thought I’d list out some products that can be used in high pressure applications for EMI/RFI Shielding. 

Product Selection for Reinforced EMI/RFI Shielding 

1. Fabric/Mesh Reinforced EMI/RFI Shielding Products

Specialty Silicone Products is a company located in New York. They have some unique products. They have a variety of Fabric Reinforced Silicone Products

-SSP-502-65-020 Nickel/Graphite, 65A Durometer with Conductive Fabric, .020’’ Thick– datasheet download

-SSP-502-65-032 Nickel/Graphite, 65A Durometer with Nickel-Coated Mesh, .032’’ Thick– datasheet download 

2. Wire Oriented Fluorosilicone/Silicone Products

These materials are offered by a number of manufacturers. These products have thousands of wires oriented perpendicular to the elastomer. Wire Oriented EMI Products do two things:

A. The wires make electrical contact with the said surfaces.

B. The wires also offer additional reinforcement that prevent the gasket from being squeezed too hard and extruding.

3. Expanded Wire EMI Shielding Products

These materials are offered in a variety of fluorosilicone/silicone/neoprene products along with other wire materials. These are usually much thinner profiles than the previous two materials. Offered in thicknesses .016’’ , .020’’ . 

These expanded wire, or expanded mesh EMI materials operate very similiar to the way the oriented wire EMI gaskets do. The wire embedded in the elastomer make electrical contact with the EMI shielded enclosure, and provided good electrical contact across the assembly. 

Specifications offered with Expanded EMI Shielding Gasket Products

Solid Rubber Elastomers:

AMS-3302D, Solid Silicone Rubber

AMS-3222, Solid Neoprene Rubber

MIL-R-25988/MIL-DTL-25988 Class 1 Type 2 Grade 40

Metals for Expanded Wire/Woven Wire

Alloy 5056, AMS-4182, Aluminum

QQ-A-250/2 3003 AL, Aluminum 

Monel, QQ-N-281 (expanded wire)

Note: It is not required to have a pressure seal when purchasing woven wire aluminum, or other metals. Its available for purchase with just the metal itself for an EMI gasket. 

emi/rfi gasketing enclosure

emi/rfi gasketing enclosure

Applications for EMI/RFI Reinforced Gaskets

-Military Grade Connector Gaskets for wall mount receptcles 

-High Pressure EMI Joints/Gaskets

Are these EMI Reinforced Products provided with Adhesive Tape Backing?

Adhesive Backing is available on these EMI/RFI reinforced products. However, it is good to note that are lot of these EMI/RFI products have wire that under pressure will cut through the adhesive it make good contact with the opposing metal without an electrically conductive tape, or an electrically conductive transfer tape.  The wires provide dozens of points of contact per square inch, making great electrical connections across the application.

More Information

NEDC die-cuts, and waterjet-cuts EMI gaskets for customers through build to print parts. For more information on EMI Gaskets with reinforcement, please contact sales@nedc.com.

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